A tape drive configured to accurately position a head actuator in the presence of physical disturbances is disclosed. The tape drive includes a track-follow controller to position a head actuator over data tracks on magnetic tape. The tape drive further includes a disturbance observer configured to estimate a vibration disturbance and output a compensation signal to assist the track-follow controller to accurately position the head actuator over the data tracks in the presence of vibration. When estimating the vibration disturbance, the disturbance observer takes into account vibration frequency characteristics, such as frequency characteristics derived from a vibration specification associated with the tape drive, or frequency characteristics derived from known vibration disturbances experienced by the tape drive. A corresponding method is also disclosed.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A tape drive for accurately positioning a head actuator in the presence of physical disturbances, the tape drive comprising: a track-follow controller to position a head actuator over data tracks on magnetic tape; a disturbance observer configured to estimate a vibration disturbance and output a compensation signal to assist the track-follow controller to accurately position the head actuator over the data tracks in the presence of vibration, the disturbance observer comprising a filter that incorporates an inverted actuator model into the filter design.
2. The tape drive of claim 1 , wherein the disturbance observer is further configured to apply a weighting profile to an actual vibration experienced by the head actuator to produce a weighted vibration signal, the weighting profile derived from a vibration specification associated with the tape drive.
3. The tape drive of claim 1 , wherein the disturbance observer is further configured to apply a weighting profile to an actual vibration experienced by the head actuator to produce a weighted vibration signal, the weighting profile derived from a known vibration disturbance experienced by the tape drive.
4. The tape drive of claim 1 , wherein the filter utilizes one of an H2 filter framework and a Kalman filter framework to estimate vibration disturbance.
5. The tape drive of claim 1 , wherein the filter utilizes a H∞ filter framework to estimate the vibration disturbance.
6. The tape drive of claim 5 , wherein the H∞ filter framework attempts to minimize a difference between an actual vibration of the head actuator and an estimated vibration of the head actuator.
7. The tape drive of claim 1 , wherein the disturbance observer receives as inputs a control input, controlling the head actuator, and a position measurement signal, indicating a position of the head actuator with respect to the magnetic tape.
8. The tape drive of claim 1 , wherein the compensation signal is added to an output of the track-follow controller.
9. The tape drive of claim 1 , wherein the compensation signal is configured to compensate for both tape-to-head skew and lateral vibrations within the tape drive.
10. The tape drive of claim 1 , wherein the track-follow controller comprises a first controller to operate under vibration conditions and a second controller to operate under non-vibration conditions, and the compensation signal describing the estimated vibration disturbance is used to switch between the first and second controllers.
11. A method for accurately positioning a head actuator in the presence of physical disturbances, the method comprising: providing a track-follow controller to position a head actuator over data tracks on magnetic tape; estimating a vibration disturbance and outputting a compensation signal to assist the track-follow controller to accurately position the head actuator in the presence of vibration, wherein estimating the vibration disturbance comprises using a filter that incorporates an inverted actuator model into the filter design to estimate the vibration disturbance.
12. The method of claim 11 , further comprising applying a weighting profile to an actual vibration experienced by the head actuator to produce a weighted vibration signal, the weighting profile derived from a vibration specification of a tape drive.
13. The method of claim 11 , further comprising applying a weighting profile to an actual vibration experienced by the head actuator to produce a weighted vibration signal, the weighting profile derived from an actual vibration disturbance.
14. The method of claim 11 , wherein estimating the vibration disturbance comprises utilizing one of an H2 filter framework and a Kalman filter framework to estimate the vibration disturbance.
15. The method of claim 11 , wherein estimating the vibration disturbance comprises utilizing a H∞ filter framework to estimate the vibration disturbance.
16. The method of claim 15 , wherein utilizing the H∞ filter framework comprises utilizing the H∞ filter framework to minimize a difference between an actual vibration of the head actuator and an estimated vibration of the head actuator.
17. The method of claim 11 , wherein estimating the vibration disturbance comprises receiving as inputs a control input, controlling the head actuator, and a position measurement signal, indicating the position of the head actuator with respect to the magnetic tape.
18. The method of claim 11 , further comprising adding the compensation signal to an output of the track-follow controller.
19. The method of claim 11 , wherein assisting the track-follow controller comprises compensating for both tape-to-head skew and lateral vibrations.
20. The method of claim 11 , wherein the track-follow controller comprises a first controller to operate under vibration conditions and a second controller to operate under non-vibration conditions, and the compensation signal describing the estimated vibration disturbance is used to switch between the first and second controllers.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
June 19, 2012
April 29, 2014
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.